Shader"Unity Shader Book/Chapter6/Diffuse Pixel Level"{
    Properties{
        _Diffuse("Diffuse", Color) = (1.0, 1.0, 1.0, 1.0)    
    }
    
    SubShader{
        Pass{
            Tags{"LightMode" = "ForwardBase"}
            
            CGPROGRAM

            #pragma vertex vert
            #pragma fragment frag
            #include "Lighting.cginc"

            fixed4 _Diffuse;
            
            struct a2v{
                float4 vertex: POSITION;
                float3 normal: NORMAL;
            };

            struct v2f{
                float4 pos: SV_POSITION;
                fixed3 worldNormal: NORMAL;
            };

            v2f vert(a2v v){
                v2f o;
                o.pos = UnityObjectToClipPos(v.vertex);
                o.worldNormal = normalize(mul(v.normal, (float3x3)unity_WorldToObject));
                return o;
            }

            fixed4 frag(v2f i): SV_Target{
                fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz;

                fixed3 worldLightDir = normalize(_WorldSpaceLightPos0.xyz);
                fixed3 worldNormal = i.worldNormal;
                fixed halfLambert = dot(worldNormal, worldLightDir) * 0.5 + 0.5;
                fixed3 diffuse = _LightColor0.rgb * _Diffuse.rgb * halfLambert;

                fixed4 color = fixed4(ambient + diffuse, 1.0);
                return color;
            }
            

            ENDCG
        }    
    }
}